1. Field of the Invention
The present invention relates to a refrigerator having a defrosting cycle, and more particularly to a method of circulating a refrigerant for defrosting and a refrigerator employing the same, in which the refrigerant compressed by a compressor is directly transferred to an evaporator to remove a frost formed on the surface of the evaporator.
2. Prior Art
Generally, a refrigerator has a cabinet having a freezer compartment and a fresh food compartment which are partioned from each other by a wall, and a freezer compartment door and a fresh food compartment door mounted on the cabinet by a hinge structure. A plularity of shelves are mounted in the freezer compartment and the fresh food compartment.
The refrigerator, as shown in FIG. 1, has a cooling system having a compressor 10 for compressing the vaporized refrigerant, an evaporator 50 for absorbing heat in the refrigerator to vaporize a refrigerant, and a condensor 20 for condensing the compressed refrigerant to emit the heat outside.
That is, the refrigerant exchanges the heat with air in the refrigerator through the evaporator 50 installed at the fresh food compartment and absorbs the heat. The refrigerant vaporized at the evaporator 50 is transferred to the compressor 10 to be compressed to a high-temperature and high-pressure gas. The compressed refrigerant is transferred to the condensor 20 to be liquefied by exchanging the heat with an outside air. The refrigerant liquefied at the condensor 20 is then passed through a drier 30 and a capillary tube 40 to change into a low-temperature and low-pressure liquid state. The refrigerant returns to the evaporator 50 to absorb a latent heat, thereby cooling the freezer and fresh food compartments.
In brief, the refrigerant absorbs the heat in the refrigerator through the evaporator 50 positioned on the fresh food compartment or the freezer compartment, and emits the absorbed heat outside through the condensor 20. During the continuous circulation of the refrigerant through the cooling system described above, the heat in the fresh food compartment and the freezer compartment is emitted outward for an effective refrigeration.
While the refrigerant exchanges the heat with air inside of the refrigerator at the evaporator 50, the difference between the temperatures of the refrigerant in the evaporator 50 and the air in the refrigerator causes a frost to be formed gradually on the surface of the evaporator 50. As a result, the frost surrounding the evaporator 50 decreases the efficiency of the heat exchange.
The operating mode of the refrigerator is switched to a defrosting mode during a predetermined period according to a defrosting signal from a controller (not shown) in order to defrost the evaporator 50.
A defrosting heater has been conventionally used to remove the frost formed on the surface of the evaporator 50. In this system, the defrosting heater is installed, and an auxiliary timer is needed to determine a switching time of the refrigerator and to control the operating time of the defrosting mode. Further, since the defrosting heater is installed at the cool air supply duct connected to the fresh food compartment, an additional accomodating space for the defrosting heater is required.
The heat generated by the operation of the defrosting heater flows into the freezer compartment to cause the temperature of the freezer compartment to increase, so that an extra refrigeration is required to prevent the temperature from increasing in the freezer compartment. Consequently, the efficiency of the compressor 10 decreases by the operation of the defrosting heater.
Another conventional defrosting system is disclosed in the Japanese Utility Model Laid-Open No. Sho 59-36481, in which refrigerant compressed to a high-temperature and high-pressure at a compressor is directly transferred to an evaporator, bypassing a condensor, and returns to the compressor after defrosting the evaporator. The system described above is superior to the defrosting heater, but since the evaporator in the defrosting cycle performs the function of the condensor, the system has a drawback in that the condensed refrigerant is difficult to vaporize before returning to the compressor.